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Thursday, September 30, 2010

I often been purchase small lots of fossils from estate sales that are from areas I've not collected at or can't get to anymore. One of the lots included some Carboniferous (Pennsylvanian) aged fossils from Texas and among them was this Neospirifer.

Neospirifer is, as the name suggests, a member of the Spiriferida order or Brachiopods and has the typical body style of a wide hinged, fan shaped shell with a deep central sulcus. An interesting fact is that Spiriferid means "Spiral Bearer" and refers to the spiral shaped lophophore supports called brachidiums.

Tuesday, September 28, 2010

So I was doing some research on Calceola, a strange genus of Devonian aged coral that has a lid, or operculum, and came across some new information that I'd not read before. Here is a good reference picture of Calceola from This Site

I'd known that these odd ball corals (that are closer to Rugose coral than Tabulate) are common from the Devonian in parts of Europe and Morocco but had never heard of them being found here in the US. As I looked through links and .pdf files I was surprised to find a reference from an 1885 Kentucky text. Click here It's a book that was published in 1885 by the Kentucky Geological Survey called "Kentucky Fossil Corals - A Monograph of the Fossil Corals of the Silurian and Devonain Rocks of Kentucky" by William J. Davis. On plate 131 are pictures of a reference specimen of Calceola sandalina along with other specimens that had been recovered from the "White Clay of Niagara" near Louisville. While all the specimens on the page are attributed be Calceola, some look like other types of rugose corals and, without examining the original specimens, I can't be sure of what they are but most do bear a resemblance to the aforementioned coral. It must be extremely rare, although I did read somewhere that they are occasionally found in Tennessee too.

The specimens that I have in my collection come from the Devonian of Morocco. Here is a large example that is missing it's lid (not uncommon).

And this specimen still has the lid in place:

This fossil has the septae lines preserved along the walls of the coral.

The other bit of info was a paper that discussed the Ontogenetic development (The origin and development of an individual organism from embryo to adult) of Calceola. As I was reading through I learned that Calceola was one of the last genera from a line of these "lidded corals" that extended to Cambrian time through to the middle Fransian stage of the upper Devonian. It also conjectured that the individual animals lived with the flat side of the coral on the surface of the sea floor rather than being upright like a Rugose coral. It has some good illustrations of the life habit of the animal (see image below) as well as passing reference to other species of these corals.

This reference from Steinkern.de has some good pics of specimens and a little info about the genera from Germany (although it's in German and so you will want to translate it with Babelfish or another translating service.)

Sunday, September 26, 2010

Recently a friend of mine on the Fossil Forum site asked me what the difference was between Atrypa and Pseudoatrypa. He has been looking for a Pseduoatrypa from the Arkona/Widder formations and wanted to be sure that he was able to tell it apart from Atrypa. The way I tell the difference between the two genera is the shape of the shell. Pseudoatrypa has a much deeper, domed brachial valve and flatter pedicle valve than Atrypa. Also Atrypa is more round shaped while Pseudoatrypa is more box shaped when viewed from the top down. Here are some pics of a side by side comparison of samples from the similar aged Silica Shale of Sylvania, Ohio.

Brachial valve

Front

Pedicle valve

Back

Side

This is a group shot for scaling purposes with the two above shells side by side in the top row. I also included a sample of each genera from my local upper Silurian/ lower Devonian Keyser formation for comparison in the bottom row. I think they started small and got larger as the Devonian wore on. The monster on the far left is from the middle Devonian of Iowa and is called Desquamatia (Independatrypa) and is included to show you just how big some of these genera became. The Canadian quarter used to show scale is equivalent in size to the American quarter or the one Euro coin.

Friday, September 24, 2010

My previous post explained my trip and the local geology so this one will be about the fossils I found.

I'll start with the greenish oysters that I left off with in my last post. These seems to be two different species.

The first is Ostrea compressirostra which is identified by it's wide flattened valves:

The second is Gryphaeostrea vomer which has a fuller profile than O. compressirostra:

As Oysters are wont to do, it's easy to find the shells clustered and growing on/with each other:

Some sections of the sediments have been cemented with leached iron from overlying sediments. This seems to have been the case with a layer that is profuse with Turritella fossils as the internal molds are very abundant on the beach resembling corkscrews.

Here is a chunk of matrix with a Turritella internal mold preserved in situ.

Some clam shells had been preserved in the same way and their internal molds were occasionally found as well:

One of the more fascinating fossils were the spiderweb like remains of the shell boring sponge Cliona. They had been preserved as though hovering above the internal shell molds like a net holding a precious cargo:

More Sand Shark teeth were found with one poking out of the cliff face:

My find for the day was this extinct Mackerel shark tooth Otodus obliquus that I found lying next to my backpack.

This site was very productive for me on this trip and I will definitely visit it again in the near future when the tides are low.

Wednesday, September 22, 2010

Recently I visited the Potomac river in Maryland to check out a river exposure of the upper Paleocene aged Aquia Formation. There are many exposures of Tertiary period sediments along the Potomac river and Chesapeake Bay but most are only accessible via watercraft. A friend from the Fossil Forum suggested a good area that I could reach on foot as I have no kayak or other boat to navigate the river.

The river was calm as was the weather with a sunny low 80's forecast for the day.

I walked along the beach stopping every now and again to closely examine the gravel along the tide line. I found my first tooth quickly:

It was a small one as were several others I found as I continued down the beach dodging the fallen trees as I went.

As I continued I came up to some sheer cliffs that exposed the formation and the plethora of mollusk shells contained within. You can large blocks of the cliff that have fallen and can be more easily picked over at the base.

This picture shows you the strata of the cliffs with a basal unit that is full of greenish Glauconite clay and it grades (somewhat abruptly) into lighter colored sandy sediments.

Most of the Tertiary sediments that are exposed along the east coast of the United States are generally unconsolidated (not turned to rock yet). The exceptions are limestone or coquina rock which have been cemented with calcium carbonate. At this location we have sandy marls that are full of mollusk shells. I could see cross sections of clams and Gastropods as well as some more complete shells, but they were all soft and crumbled at my touch. This was likely due to exposure to weathering which leached much of the calcium carbonate from the shells and left them friable. This is not an uncommon occurrence in unconsolidated sediments but can vary from site to site due to regional differences in weathering and original deposition.

Here a Turitella sp. gastropod shell is exposed. You can see that it's very fragile and part has already broken off with the rest soon to follow. It's little to no use trying to salvage blocks of the sediment as the shells crumble whether they are wet or dry.

In fallen blocks of the cliff you could see horizontal sections of the sediments, but the results were similar. I did collect a few small pieces of matrix and I need to soak them in a liquid consolidator and maybe that will help preserve the delicate shells.

In this picture you can see some greenish oyster shells preserved in the sediment along with the gastropods and clams. Surprisingly the oysters are very solid and easily collected.

They often weather out of the cliffs intact and can be found at the base or along the tide line easily. I'll post some pictures of them and some of the other fossils I found in my next post.

About Me

I'm a 40-something, life long student of Geology living in Philadelphia. My interests include Photography, Architecture and History among other things. When not cleaning my recent finds you'll find me in my backyard Hybridizing Daylilies or working in my garden. This Blog is an outlet for me to express my interest in fossils, catalog my collection and coalesce my thoughts and research into a useful medium.